Damascene method of forming a semiconductor structure and a semiconductor structure with multiple fin-shaped channel regions having different widths

ABSTRACT

Disclosed is a damascene method for forming a semiconductor structure and the resulting semiconductor structure having multiple fin-shaped channel regions with different widths. In the method, fin-shaped channel regions are etched using differently configured isolating caps as masks to define the different widths. For example, a wide width isolating cap can comprise a dielectric body positioned laterally between dielectric spacers and can be used as a mask to define a relatively wide width channel region; a medium width isolating cap can comprise a dielectric body alone and can be used as a mask to define a medium width channel region and/or a narrow width isolating cap can comprise a dielectric spacer alone and can be used as a mask to define a relatively narrow width channel region. These multiple fin-shaped channel regions with different widths can be incorporated into either multiple multi-gate field effect transistors (MUGFETs) or a single MUGFET.

BACKGROUND

1. Field of the Invention

The present invention relates to embodiments of a damascene method offorming a semiconductor structure and to embodiments of a semiconductorstructure with multiple fin-shaped channel regions having differentwidths.

2. Description of the Related Art

Integrated circuit design decisions are often driven by devicescalability and manufacturing efficiency. For example, because sizescaling of planar field effect transistors (FETs) resulted in reduceddrive current as a function of reduced channel width, non-planarmulti-gate field effect transistors (MUGFETs) (e.g., dual-gate FETs andtri-gate FETs) were developed to provide scaled devices with increaseddrive current and reduced short channel effects. A dual-gate FET (alsoreferred to as a fin-type FET or FINFET) is a non-planar FET comprisinga relatively thin semiconductor fin with a channel region at the centerof the fin positioned laterally between source/drain regions at the endsof the fin. A gate structure is adjacent to the opposing sides of thechannel region and an isolating cap is on the top surface of the channelregion. Thus, the dual-gate FET exhibits two-dimensional field effects.A tri-gate FET is similar in structure to a dual-gate FET. However, thesemiconductor fin of a tri-gate FET is typically wider and the gatestructure is adjacent to both the opposing sides and the top surface ofthe channel region. Thus, the tri-gate FET exhibits three-dimensionalfield effects.

During MUGFET processing, device performance can be tuned by adjustingthe width of the semiconductor fin in the source/drain regions and/orchannel region and also by incorporating multiple semiconductor finsinto a single MUGFET. Unfortunately, tuning device performance in thismanner is limited by current MUGFET processing techniques. For example,if one or more relatively thin semiconductor fins are formed for adual-gate or tri-gate FET and then one or more dopant implantationprocesses (e.g., source/drain extension implantation, halo implantation,source/drain implantation, etc.) are performed, fin damage can occur.The risk of damage increases significantly as the fin width within thechannel region decreases. Therefore, there is a need in the art for animproved method of forming MUGFETs.

SUMMARY

In view of the foregoing, disclosed herein are embodiments of adamascene method for forming a semiconductor structure and also theresulting semiconductor structure having multiple fin-shaped channelregions with different widths. During damascene processing and,particularly, after source/drain and other dopant implantation processesare performed, fin-shaped channel regions are etched using differentlyconfigured isolating caps as masks to define the different channelregion widths. For example, a wide width isolating cap can comprise adielectric body positioned laterally between dielectric spacers and canbe used as a mask to define a relatively wide width channel region; amedium width isolating cap can comprise a dielectric body alone and canbe used as a mask to define a medium width channel region and/or anarrow width isolating cap can comprise a dielectric spacer alone andcan be used as a mask to define a relatively narrow width channelregion. These multiple fin-shaped channel regions with different widthscan be incorporated into either multiple different non-planar multi-gatefield effect transistors (MUGFETs) or a single MUGFET. By defining thefin-shaped channel regions after source/drain and other dopantimplantation processes are performed, channel region damage can beavoided.

One embodiment of a method of forming a semiconductor structure havingmultiple fin-shaped channel regions with different widths can compriseproviding a semiconductor layer on an insulator layer. A trenchisolation structure can be formed so as to define, in the semiconductorlayer, a first semiconductor region for a first non-planar multi-gatefield effect transistor (MUGFET) and a second semiconductor region,positioned laterally adjacent to the first semiconductor region, for asecond MUGFET.

After the first semiconductor region and second semiconductor region aredefined, a first dielectric body can be formed on the firstsemiconductor region and at the same time a second dielectric body canbe formed on the second semiconductor region. The first dielectric bodyand the second dielectric body can specifically be formed so that theyare essentially identical, so that they traverse the length of the firstsemiconductor region and second semiconductor region, respectively, andfurther so that they are narrower than the first semiconductor regionand the second semiconductor region, respectively. Once the firstdielectric body and second dielectric body are formed, first dielectricspacers can be formed on first opposing sides of the first dielectricbody.

Next, a sacrificial layer can be formed so that it traverses the centerportion of the first semiconductor region (i.e., the first centerportion), leaving the end portions of the first semiconductor region(i.e., the first end regions) exposed and so that it traverses thecenter portion of the second semiconductor region (i.e., the secondcenter portion), leaving the end portions of the second semiconductorregion (i.e., the second end portions) exposed. It should be noted thatthis process will remove all dielectric material (i.e., the firstdielectric body, first dielectric spacers, and second dielectric body)from above the first and second end portions, while leaving thedielectric material above the first and second center portions. Afterthe sacrificial layer is formed, a blanket dielectric layer can beformed over the sacrificial layer, the first end portions and the secondend portions and, then, planarized to expose the sacrificial layer. Onceexposed, the sacrificial layer can be selectively removed.

Next, a directional etch process can be performed so as to removeexposed semiconductor material within the first center portion and thesecond center portion. During this directional etch process, thedielectric layer on the first end portions and the second end portions,the first dielectric body and the first dielectric spacers on the firstcenter portion and the second dielectric body on the second centerportion are used as masks. As a result, the first center portion will beessentially fin-shaped and will have a first width that is essentiallyequal to the combined width of the first dielectric spacers and firstdielectric body. Also as a result, the second center portion will beessentially fin-shaped and will have a second width that is less thanthe first width and that is essentially equal to the width of the secondsemiconductor body.

Once the directional etch process is performed, a gate structure can beperformed adjacent to the first center portion to complete the firstMUGFET and adjacent to the second center portion to complete the secondMUGFET. In this case the resulting first and second MUGFETs will bedual-gate FETs because the dielectric material on the top surfaces ofthe first and second center portions (i.e., the first dielectric bodyand first dielectric spacers on the first center portion and the seconddielectric body on the second center portion) will function as isolatingcaps. However, optionally, prior to gate structure formation, alldielectric material can be selectively removed from above the firstcenter portion and/or the second center portion so as to form tri-gateFET(s) instead of dual-gate FET(s).

An embodiment of a semiconductor structure formed according to thismethod embodiment can comprise a first semiconductor region for a firstnon-planar multi-gate field effect transistor (MUGFET) and a secondsemiconductor region, positioned laterally adjacent to the firstsemiconductor region, for a second MUGFET. The first semiconductorregion and the second semiconductor region can be defined by a trenchisolation structure. That is, a trench isolation structure on theinsulator layer can laterally surround the first semiconductor regionand the second semiconductor region such that the first semiconductorregion is electrically isolated from the second semiconductor region.The first semiconductor region can have first end portions and a firstcenter portion positioned laterally between the first end portions. Thefirst center portion can be narrower than the first end portions (e.g.,can be essentially fin-shaped) and can have a first width. Optionally, afirst isolating cap can be positioned on the first center portion andcan have the same first width. The first isolating cap can comprise adielectric body positioned laterally between dielectric spacers. Thesecond semiconductor region can have second end portions and a secondcenter portion positioned laterally between the second end portions. Thesecond center portion can be narrower than the second end portions(e.g., can be essentially fin-shaped) and can have a second width thatis less than the first width. Optionally, a second isolating cap bepositioned on the second center portion and can have the same secondwidth. The second isolating cap can be essentially identical to thedielectric body of the first isolating cap.

Another embodiment of a method of forming a semiconductor structurehaving multiple fin-shaped channel regions with different widths cansimilarly comprise providing a semiconductor layer on an insulatorlayer. A trench isolation structure can be formed so as to define, inthe semiconductor layer, a first semiconductor region for a first fieldeffect transistor and a second semiconductor region, positionedlaterally adjacent to the first semiconductor region, for a second fieldeffect transistor.

After the first semiconductor region and second semiconductor region aredefined, a first dielectric body can be formed on the firstsemiconductor region and at the same time a second dielectric body canbe formed on the second semiconductor region. The first dielectric bodyand the second dielectric body can specifically be formed so that theyare essentially identical, so that they traverse the length of the firstsemiconductor region and second semiconductor region, respectively, andfurther so that they are narrower than the first semiconductor regionand the second semiconductor region, respectively. Once the firstdielectric body and second dielectric body are formed, first dielectricspacers can be formed on first opposing sides of the first dielectricbody and at the same time second dielectric spacers can be formed onsecond opposing sides of the second dielectric body. After the first andsecond dielectric spacers are formed, the second dielectric body can beselectively removed from the second dielectric spacers.

Next, a sacrificial layer can be formed so that it traverses the centerportion of the first semiconductor region (i.e., the first centerportion), leaving the end portions of the first semiconductor region(i.e., the first end portions) exposed and also so that it traverses thecenter portion of the second semiconductor region (i.e., the secondcenter portion), leaving the end portions of the second semiconductorregion (i.e., the second end portions) exposed. It should be noted thatthis process will remove all dielectric material (i.e., the firstdielectric body, first dielectric spacers, and second dielectricspacers) from above the first and second end portions, while leaving thedielectric material above the first and second center portions. Afterthe sacrificial layer is formed, a blanket dielectric layer can beformed over the sacrificial layer, the first end portions and the secondend portions and, then, planarized to expose the sacrificial layer. Onceexposed, the sacrificial layer can be selectively removed.

Next, a directional etch process can be performed so as to removeexposed semiconductor material within the first center portion and thesecond center portion. During this directional etch process, thedielectric layer on the first end portions and the second end portions,the first dielectric body and the first dielectric spacers on the firstcenter portion and the second spacers on the second center portion areused as masks. As a result, the first center portion will be essentiallyfin-shaped and will have a first width equal to the combined width ofthe first dielectric spacers and first dielectric body and the secondcenter portion will have two parallel sections, each section beingessentially fin-shaped and having a second width that is less than thefirst width and equal to the width of one of the second dielectricspacers.

Once the directional etch process is performed, a gate structure can beperformed adjacent to the first center portion to complete the firstMUGFET and adjacent to the second center portion to complete the secondMUGFET. In this case the resulting first and second MUGFETs will bedual-gate FETs because the dielectric material on the top surfaces ofthe first and second center portions (i.e., the first dielectric bodyand first dielectric spacers on the first center portion and the seconddielectric spacers on the parallel sections of the second centerportion) will function as isolating caps. However, optionally, prior togate structure formation, all dielectric material can be selectivelyremoved from above the first center portion and/or the second centerportion so as to form tri-gate FET(s) instead of dual-gate FET(s).

An embodiment of a semiconductor structure formed according to thismethod embodiment can comprise a first semiconductor region for a firstnon-planar multi-gate field effect transistor (MUGFET) and a secondsemiconductor region, positioned laterally adjacent to the firstsemiconductor region, for a second MUGFET. The first semiconductorregion and the second semiconductor region can be defined by a trenchisolation structure. That is, a trench isolation structure on theinsulator layer can laterally surround the first semiconductor regionand the second semiconductor region such that the first semiconductorregion is electrically isolated from the second semiconductor region.The first semiconductor region can have first end portions and a firstcenter portion positioned laterally between the first end portions. Thefirst center portion can be narrower than the first end portions (e.g.,can be essentially fin-shaped) and can have a first width. Optionally, afirst isolating cap can be positioned on the first center portion andcan have the same first width. The first isolating cap can comprise adielectric body positioned laterally between dielectric spacers. Thesecond semiconductor region can have second end portions and a secondcenter portion positioned laterally between the second end portions. Thesecond center portion can be narrower than the second end portions andcan comprise two parallel sections. Each of these parallel sections canbe essentially fin-shaped and can have a second width that is less thanthe first width. Optionally, second isolating caps can be positioned onthe parallel sections and can have the same second width. Each secondisolating cap can be essentially identical to one of the dielectricspacers of the first isolating cap.

The above-described method embodiments form the multiple fin-shapedchannel regions with different widths on different semiconductor regions(i.e., a first semiconductor region and a second semiconductor region).However, it should be understood that similar techniques could also beused to form such multiple fin-shaped channel regions with differentwidths on the same semiconductor region. Thus, also disclosed herein areembodiments of a semiconductor structure that comprises a semiconductorregion. The semiconductor region can be defined by a trench isolationstructure. That is, a trench isolation structure can laterally surroundthe semiconductor region. The semiconductor region can have end portionsand a center portion positioned laterally between the end portions. Thecenter portion can be narrower than the end portions and can comprise aplurality of parallel essentially fin-shaped sections. At least two ofthe parallel sections can have different widths. Optionally, a firstisolating cap, having a first width, can be positioned on a first one ofthe parallel sections, having the same first width. The first isolatingcap can comprise a dielectric body positioned laterally betweendielectric spacers. Optionally, a second isolating cap, having a secondwidth that is less than the first width, can be positioned on a secondone of the parallel sections, having the same second width. This secondisolating cap can be essentially identical to either the dielectric bodyof the first isolating cap or essentially identical to one of thedielectric spacers of the first isolating cap.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The embodiments disclosed herein will be better understood withreference to the drawings, which are not necessarily drawn to scale andin which:

FIG. 1 is a flow diagram illustrating an embodiment of a damascenemethod of forming a semiconductor structure;

FIG. 2A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 1;

FIG. 2B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 2A;

FIG. 3A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 1;

FIG. 3B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 3A;

FIG. 4A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 1;

FIG. 4B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 4A;

FIG. 5A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 1;

FIG. 5B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 5A;

FIG. 6A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 1;

FIG. 6B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 6A;

FIG. 7 is a top view drawing of a partially completed semiconductorstructure formed according to the method of FIG. 1;

FIG. 8 is a top view drawing of a partially completed semiconductorstructure formed according to the method of FIG. 1;

FIG. 9A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 1;

FIG. 9B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 9A;

FIG. 10A is a vertical cross-section drawing illustrating a partiallycompleted semiconductor structure formed according to the method of FIG.1;

FIG. 10B is a horizontal cross-section drawing of the same partiallycompleted semiconductor structure as shown in FIG. 10A;

FIG. 10C is another horizontal cross-section drawing of the samepartially completed semiconductor structure as shown in FIG. 10A;

FIG. 11A is a vertical cross-section drawing illustrating a completedsemiconductor structure formed according to the method of FIG. 1;

FIG. 11B is a horizontal cross-section drawing of the same completedsemiconductor structure as shown in FIG. 11A;

FIG. 11C is another horizontal cross-section drawing of the samecompleted semiconductor structure as shown in FIG. 11A;

FIG. 11D is yet another horizontal cross-section drawing of the samecompleted semiconductor structure as shown in FIG. 11A;

FIG. 12 is a flow diagram illustrating another embodiment of a damascenemethod of forming a semiconductor structure;

FIG. 13A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 12;

FIG. 13B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 13A;

FIG. 14A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 12;

FIG. 14B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 14A;

FIG. 15A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 12;

FIG. 15B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 15A;

FIG. 16 is a top view drawing of a partially completed semiconductorstructure formed according to the method of FIG. 12;

FIG. 17 is a top view drawing of a partially completed semiconductorstructure formed according to the method of FIG. 12;

FIG. 18A is a cross-section drawing illustrating a partially completedsemiconductor structure formed according to the method of FIG. 12;

FIG. 18B is a top view drawing of the same partially completedsemiconductor structure as shown in FIG. 18A;

FIG. 19A is a vertical cross-section drawing illustrating a partiallycompleted semiconductor structure formed according to the method of FIG.12;

FIG. 19B is a horizontal cross-section drawing of the same partiallycompleted semiconductor structure as shown in FIG. 19A;

FIG. 19C is another horizontal cross-section drawing of the samepartially completed semiconductor structure as shown in FIG. 19A;

FIG. 20A is a vertical cross-section drawing illustrating a completedsemiconductor structure formed according to the method of FIG. 12;

FIG. 20B is a horizontal cross-section drawing of the same completedsemiconductor structure as shown in FIG. 20A;

FIG. 21A is a vertical cross-section drawing illustrating anothercompleted semiconductor structure form using similar techniques as shownin FIGS. 1 and 12; and

FIG. 21B is a horizontal cross-section drawing of the same completedsemiconductor structure as shown in FIG. 21A.

DETAILED DESCRIPTION

The embodiments of the invention and the various features andadvantageous details thereof are explained more fully with reference tothe non-limiting embodiments that are illustrated in the accompanyingdrawings and detailed in the following description.

As discussed above, integrated circuit design decisions are often drivenby device scalability and manufacturing efficiency. For example, becausesize scaling of planar field effect transistors (FETs) resulted inreduced drive current as a function of reduced channel width, non-planarmulti-gate field effect transistors (MUGFETs) (e.g., dual-gate FETs andtri-gate FETs) were developed to provide scaled devices with increaseddrive current and reduced short channel effects. A dual-gate FET (alsoreferred to as a fin-type FET or FINFET) is a non-planar FET comprisinga relatively thin semiconductor fin with a channel region at the centerof the fin positioned laterally between source/drain regions at the endsof the fin. A gate structure is adjacent to the opposing sides of thechannel region and an isolating cap is on the top surface of the channelregion. Thus, the dual-gate FET exhibits two-dimensional field effects.A tri-gate FET is similar in structure to a dual-gate FET. However, thesemiconductor fin of a tri-gate FET is typically wider and the gatestructure is adjacent to both the opposing sides and the top surface ofthe channel region. Thus, the tri-gate FET exhibits three-dimensionalfield effects.

During MUGFET processing, device performance can be tuned by adjustingthe width of the semiconductor fin in the source/drain regions and/orchannel region and also by incorporating multiple semiconductor finsinto a single MUGFET. Unfortunately, tuning device performance in thismanner is limited by current MUGFET processing techniques. For example,if one or more relatively thin semiconductor fins are formed for adual-gate or tri-gate FET and then one or more dopant implantationprocesses (e.g., source/drain extension implantation, halo implantation,source/drain implantation, etc.) are performed, fin damage can occur.The risk of damage increases significantly as the fin width within thechannel region decreases. Therefore, there is a need in the art for animproved method of forming MUGFETs.

In view of the foregoing, disclosed herein are embodiments of adamascene method for forming a semiconductor structure and also theresulting semiconductor structure having multiple fin-shaped channelregions with different widths. During damascene processing and,particularly, after source/drain and other dopant implantation processesare performed, fin-shaped channel regions are etched using differentlyconfigured isolating caps as masks to define the different channelregion widths. For example, a wide width isolating cap can comprise adielectric body positioned laterally between dielectric spacers and canbe used as a mask to define a relatively wide width channel region; amedium width isolating cap can comprise a dielectric body alone and canbe used as a mask to define a medium width channel region and/or anarrow width isolating cap can comprise a dielectric spacer alone andcan be used as a mask to define a relatively narrow width channelregion. These multiple fin-shaped channel regions with different widthscan be incorporated into either multiple different non-planar multi-gatefield effect transistors (MUGFETs) or a single MUGFET. By defining thefin-shaped channel regions after source/drain and other dopantimplantation processes are performed, channel region damage can beavoided even with device size scaling.

More particularly, referring to FIG. 1, one embodiment of a method offorming a semiconductor structure with multiple fin-shaped channelregions having different widths can comprise providing asemiconductor-on-insulator (SOI) wafer (12). This SOI wafer cancomprise, for example, a semiconductor substrate (e.g., a siliconsubstrate or other suitable semiconductor substrate), an insulator layer(e.g., a buried oxide (BOX) layer or other suitable insulator layer) onthe substrate and a semiconductor layer on an insulator layer.

Next, a trench isolation structure 110 (e.g., a shallow trench isolation(STI) structure) can be formed so as to define, in the semiconductorlayer on the insulator layer 105, a first semiconductor region 120 a fora first non-planar multi-gate field effect transistors (MUGFET) and asecond semiconductor region 120 b, positioned laterally adjacent to thefirst semiconductor region 120 a, for a second MUGFET (14, see FIGS. 2Aand 2B). This isolation structure 110 can specifically be formed so thatit extends vertically through the semiconductor layer to the insulatorlayer 105, so that it laterally surrounds and defines an essentiallyrectangular-shaped first semiconductor region 120 a and also so that itlaterally surrounds and defines an essentially rectangular-shaped secondsemiconductor region 120 b. Thus, the isolation structure 110 is formedso that it electrically isolates the first semiconductor region 120 afrom the second semiconductor region 120 b. It should be noted that thefirst semiconductor region 120 a and second semiconductor region 120 canbe defined (e.g., by lithographic patterning of the isolation structure110) so that their widths 142 a and 142 b are essentially the same andso that their lengths are also essentially the same (as shown).Alternatively, the semiconductor regions 120 a and 120 b can be defined(e.g., by lithographic patterning of the isolation structure 110) sothat their widths and/or lengths are different (not shown). Processingtechniques for forming such a trench isolation structure 110 and,particularly, an STI structure are well-known in the art and are omittedfrom this specification in order to allow the reader to focus on thesalient aspects of the invention.

After the first semiconductor region 120 a and second semiconductorregion 120 b are defined at process 14, a first dielectric body 151 acan be formed on the first semiconductor region 120 a and at the sametime a second dielectric body 151 b can be formed on the secondsemiconductor region 120 b (16, see FIGS. 3A and 3B). The firstdielectric body 151 a and the second dielectric body 151 b canspecifically be formed so that they are essentially identical, so thatthey traverse the length of the first semiconductor region 120 a andsecond semiconductor region 120 b, respectively, and further so thatthey are narrower than the first semiconductor region 120 a and thesecond semiconductor region 120 b, respectively. This can beaccomplished, for example, by depositing a first dielectric hardmasklayer and, then, patterning the first dielectric hardmask layerlithographically to create the discrete dielectric bodies 151 a-b.

Once the first dielectric body 151 a and second dielectric body 151 bare formed, first dielectric spacers 152 a can be formed on firstopposing sides 153 a of the first dielectric body 152 a (18, see FIGS.5A-5B). However, processing should specifically be performed so thatfollowing this method step 18, dielectric spacers are not positionedlaterally adjacent to opposing sides 153 b of the second dielectric body151 b.

For example, a conformal second dielectric hardmask layer can bedeposited. This second dielectric hardmask layer can comprise adifferent dielectric hardmask material than the first dielectrichardmask layer that was previously used at process 16 to form the firstand second dielectric bodies 151 a-b. The second dielectric hardmasklayer can be selectively and anisotropically etched to form firstdielectric spacers 152 a on the opposing sides 153 a of the firstdielectric body 151 a and second dielectric spacers 152 b on theopposing sides 153 b of the second dielectric body 151 b (see FIGS. 4Aand 4B). Then, the first semiconductor region 120 a can be masked andthe second dielectric spacers 152 b can be selectively removed (seeFIGS. 5A and 5B). Alternatively, a mask can be formed over the secondsemiconductor region 120 b. Then, a second dielectric hardmask layer canbe deposited over the first semiconductor region 120 a. Again, thissecond dielectric hardmask layer can comprise a different dielectrichardmask material than the first dielectric hardmask layer that waspreviously used at process 16 to form the first and second dielectricbodies 151 a-b. The second dielectric hardmask layer can then beselectively and anisotropically etched to form first dielectric spacers152 a on the opposing sides 153 a of the first dielectric body only andthe mask can be selectively removed.

As mentioned above, the dielectric bodies 151 a-b and the dielectricspacers 152 a-b should be formed so that they comprise differentdielectric materials and, particularly, different dielectric materialsthat allow for selective etching of the dielectric spacers over thedielectric bodies. For example, the dielectric bodies 151 a-b can beformed with silicon nitride and the dielectric spacers 152 a-b can beformed with silicon oxide, silicon oxynitride or silicon carbide. Theseexemplary dielectric materials are offered for illustration purposesonly and it should be understood that other combinations of dielectricmaterials may alternatively be used.

Next, a sacrificial layer 195 (i.e., a sacrificial gate structure, areplacement gate structure, etc.) can be formed (20, see FIGS. 6A-6B).This sacrificial layer can comprise, for example, a polysilicon layer orother material that can be selectively etched at process 214, discussedbelow. Specifically, this sacrificial layer 195 can be deposited andpatterned (e.g., lithographically) so that it traverses the centerportion 131 a (i.e., the first center portion or first designatedchannel region) of the first semiconductor region 120 a covering thefirst dielectric body 151 a and first dielectric spacers 152 a and alsoso that it traverses the center portion 131 b (i.e., the second centerportion or second designated channel region) of the second semiconductorregion 120 b covering the second dielectric body 151 b. Thus, the endportions 132 a of the first semiconductor region 120 a (i.e., the firstend portions) and also the end portions 132 b of the secondsemiconductor region 120 b (i.e., the second end portions) will remainexposed. It should be noted that this process 210 will remove alldielectric material (i.e., the first dielectric body 151 a, firstdielectric spacers 152 a, and second dielectric body 151 b) from abovethe first and second end portions 132 a-b, while leaving intact thedielectric material above the first and second center portions 131 a-b.

After the sacrificial layer 195 is formed at process 20, conventionalMUGFET processing can be performed (22). This conventional MUGFETprocessing can include, but is not limited to, source/drain extensiondopant implantation, halo dopant implantation, gate sidewall spacer 162formation (see FIG. 7), source/drain dopant implantation into the firstand second end portions 132 a-b and silicide layer formation on the topsurfaces of the first and second end portions 132 a-b. It should benoted that this conventional processing will vary depending upon whetherthe MUGFETs being formed in the first semiconductor region 120 a and thesecond semiconductor region are to have the same conductivity type(e.g., n-type or p-type) or opposite conductivity types (e.g., n-typeand p-type, respectively). For example, if the MUGFETs are to have thesame conductivity type the various dopant implantation processes can beperformed essentially simultaneously. However, if the MUGFETs are tohave opposite conductivity types, the end portions of one semiconductorregion can be masked while dopant implantation is performed on the endportions of the other semiconductor region and vice versa.

Next, a blanket dielectric layer 115 (e.g., an interlayer dielectric)can be formed (e.g., deposited) such that it extends over thesacrificial layer 195, the gate sidewall spacers 162, the first endportions 132 a and the second end portions 132 b. The blanket dielectriclayer 115 can then be planarized (e.g., using a conventional chemicalmechanical polishing (CMP) process) to expose the top surface of thesacrificial layer 195 (24, see FIG. 8).

Once exposed, the sacrificial layer 195 can be selectively removed(e.g., using a selective etch process) (26, see FIGS. 9A and 9B). Thisprocess 26 exposes the remaining portions of the first dielectric body151 a and the first dielectric spacers 152 a as well as sections of thefirst center portion 131 a of the first semiconductor region 120 abetween the first dielectric spacers 152 a and the isolation structure110. This process 26 also exposes the remaining portion of the seconddielectric body 151 b as well as sections of the second center portion131 b of the second semiconductor region 120 b between the seconddielectric body 151 b and the isolation structure 110. Finally, thisprocess 26 leaves the gate sidewall spacers 162 and dielectric layer 115essentially intact.

Next, a directional etch process (e.g., a reactive ion etch (RIE)process) can be performed so as to remove exposed semiconductor materialwithin the first center portion 131 a of the first semiconductor region120 a and the second center portion 131 b of the second semiconductorregions 120 b (28, see FIGS. 10A-10C). During this directional etchprocess 28, the dielectric layer 115 on the first end portions 132 a andthe second end portions 132 b, the first dielectric body 151 a and thefirst dielectric spacers 152 a on the first center portion 131 a and thesecond dielectric body 151 b on the second center portion 131 b are usedas masks. Thus, this directional etch process 28 forms openings 196a-196 b that stop on the insulator layer 105 and, thereby turns thecenter portions 131 a-b (i.e., the channel regions) of the semiconductorregions 120 a-b, respectively, into essentially fin-shaped structures.More specifically, as a result of this directional etch process 28, thefirst center portion 131 a of the first semiconductor region 120 a willbe narrower than the first end portions 132 b and will have a firstwidth 141 a that is essentially equal to the combined width of the firstdielectric body 151 a and the first dielectric spacers 152 a. Also as aresult of this directional etch process 28, the second center portion131 b of the second semiconductor region 120 b will be narrower than thesecond end portions 132 b and will have a second width 141 b that isless than the first width 141 a and, more specifically, that isessentially equal to the width of the second dielectric body 151 b (seeFIG. 10B).

After performing the directional etch process 28, a gate structure 190can be formed on exposed first sidewalls 130 a of the first centerportion 131 a and also on exposed second sidewalls 130 b of the secondcenter portion 131 b (32, see FIGS. 11A-11B). For example, a conformalgate dielectric layer 191 (e.g., a gate oxide layer, a high-k gatedielectric layer or other suitable gate dielectric layer) can be formed(e.g., deposited) and a gate conductor layer 192 (e.g., a metal gateconductor layer, a polysilicon gate conductor layer, a dual workfunction gate conductor layer or other suitable gate conductor layer)can be formed (e.g., deposited) on the gate dielectric layer 191. Thegate conductor layer 192 and gate dielectric layer 191 can then bepatterned (e.g., lithographically), thereby creating a gate structure190 that traverses the center portions 131 a-b and fills the openings196 a-b. As a result, this gate structure 190 is positioned on the firstsidewalls 130 a of the first center portion 131 a and also on the secondsidewalls 130 b of the second center portion 131 b.

It should be noted that, in this case, the first dielectric body 151 aand first dielectric spacers 152 a will function as a first isolatingcap 150 a that electrically isolates the top surface of the first centerportion 131 a from the gate structure 190 and, thereby ensures that onlytwo-dimensional field effects are exhibited by the first center portion131 a. Similarly, the second dielectric body 151 b will function assecond isolating cap 150 b that electrically isolates the top surface ofthe second center portion 131 b from the gate structure 190 and, therebyensures that only two-dimensional field effects are exhibited by thesecond center portion 131 b. However, optionally, prior to forming thegate structure 190 at process 32, dielectric material can be selectivelyremoved from above the first center portion 131 a and/or the secondcenter portion 131 b (30). Removing this dielectric material allowsthree-dimensional field effects to be exhibited.

After the gate structure 190 is formed at process 32, additionalconventional processing can be performed in order to complete theMUGFETs 101 a-b (34). This additional processing can include, but is notlimited to, deposition of interlayer dielectric material, contactformation, etc.

FIG. 11A is vertical cross-section illustration of an embodiment of asemiconductor structure 100A formed according to the method of FIG. 1such that it has multiple fin-shaped channel regions 131 a, 131 b havingdifferent widths 141 a, 141 b and, optionally, differently configuredisolating caps 150 a, 150 b. FIGS. 11B-11D are different horizontalcross-section illustrations of the same semiconductor structure 100A.

Referring to FIG. 11A, this semiconductor structure 100A can comprise asilicon-on-insulator (SOI) structure. Specifically, the structure 100Acan comprise an insulator layer 105 (e.g., a buried oxide (BOX) layer orother suitable insulator layer) and a semiconductor layer (e.g., asilicon layer or other suitable semiconductor layer) on the insulatorlayer 105. A trench isolation structure 110 (e.g., a shallow trenchisolation (STI) structure) can extend vertically through thesemiconductor layer to the insulator layer 105 and can define a firstsemiconductor region 120 a for a first MUGFET 101 a and a secondsemiconductor region 120 b, positioned laterally adjacent to the firstsemiconductor region 120 a, for a second MUGFET 101 b (see also FIG.11B). That is, a trench isolation structure 110 on the insulator layer105 can laterally surround the first semiconductor region 120 a and thesecond semiconductor region 120 b such that the first semiconductorregion 120 a is electrically isolated from the second semiconductorregion 120 b.

The first semiconductor region 120 a can have first end portions 132 aand a first center portion 131 a positioned laterally between the firstend portions 132 a. The first center portion 131 a can comprise a firstchannel region for the first MUGFET 101 a. The first center portion 131a can further be narrower than the first end portions 132 b, can havefirst opposing sidewalls 130 a (e.g., can be essentially fin-shaped),can be physically separated from the isolation structure 110 and canhave a first width 141 a. The first end portions 132 a can comprisefirst source/drain regions and, optionally, other component regions(e.g., first halo regions, first source/drain extension regions, etc.)for the first MUGFET 101 a. Optionally, a first isolating cap 150 a canbe positioned on the top surface of the first center portion 131 a andcan have the same first width 141 a. The first isolating cap 150 a cancomprise a dielectric body 151 a positioned laterally between dielectricspacers 152 a. The first width 141 a of the first center portion 131 acan be essentially equal to the combined width of the dielectric body151 a and the dielectric spacers 152 a.

The second semiconductor region 120 b can have second end portions 132 band a second center portion 131 b positioned laterally between thesecond end portions 132 b. The second center portion 131 b can comprisea second channel region for the second MUGFET 101 b. The second centerportion 131 b can further be narrower than the second end portions 132b, can have second opposing sidewalls 130 b (e.g., can be essentiallyfin-shaped), can be physically separated from the isolation structure110 and can have a second width 141 b. The second end portions 132 b cancomprise second source/drain regions and, optionally, other componentregions (e.g., second halo regions, second source/drain extensionregions, etc.) for the second MUGFET 101 b. Optionally, a secondisolating cap 150 b be positioned on the top surface of the secondcenter portion 131 b and can have the same second width 141 b. Thesecond isolating cap 150 can be another dielectric body 151 b alone(i.e., without dielectric spacers). The dielectric body 151 b can beessentially identical to the dielectric body 151 a such that the secondwidth 141 b is less than the first width 141 a.

A gate structure 190 can traverse the center portions 131 a and 131 b ofboth semiconductor regions 120 a, 120 b. Specifically, a conformal gatedielectric layer 191 (e.g., a gate oxide layer, a high-k gate dielectriclayer or other suitable gate dielectric layer) can be positioned on thefirst opposing sidewalls 130 a of the first center portion 131 a of thefirst semiconductor region 120 a and also on the second opposingsidewalls 130 b of the second center portion 131 b of the secondsemiconductor region 120 b. A gate conductor layer 192 (e.g., a metalgate conductor layer, a polysilicon gate conductor layer, a dual workfunction gate conductor layer or other suitable gate conductor layer)can be positioned on the gate dielectric layer 191. The top surface ofthe first center portion 131 a can, optionally, be electrically isolatedfrom the gate structure 190 by the first isolating cap 150 a so that thefirst center portion 131 a exhibits only two-dimensional field effects.Without the first isolating cap 150 a, the first center portion 131 acan exhibit three-dimensional field effects. Similarly, the top surfaceof the second center portion 131 b can, optionally, be electricallyisolated from the gate structure 190 by the second isolating cap 150 bso that the second center portion 131 b also exhibits onlytwo-dimensional field effects. Without the second isolating cap 150 b,the second center portion 131 b can exhibit three-dimensional fieldeffects.

Gate sidewall spacers 162 can be positioned on opposing sides of thegate structure 190 and, optionally, metal silicide layers 161 a, 161 bcan be positioned on the top surfaces of the first end portions 132 aand second end portions 132 b, respectively (see also FIG. 11C).Finally, an interlayer dielectric material 115 can be positioned on themetal silicide layers 161 a, 161 b above the first and second endportions 132 a, 132 b of the first and second semiconductor regions 120a, 120 b, respectively, and adjacent to the gate sidewall spacers 162(see also FIG. 11D).

In the above-discussed semiconductor structure 100A, the dielectricbodies 151 a-b and the dielectric spacers 152 a can comprise differentdielectric materials and, particularly, different dielectric materialsthat allow for selective etching during processing. For example, thedielectric bodies 151 a-b can comprise silicon nitride and thedielectric spacers 152 a can comprise silicon oxide, silicon oxynitrideor silicon carbide. These exemplary dielectric materials are offered forillustration purposes only. It should be understood that othercombinations of dielectric materials may alternatively be used.Additionally, in the above-discussed semiconductor structure 100A, thefirst MUGFET 101 a and second MUGFET 101 b can be different types ofMUGFETs (e.g., an n-type MUGFET and a p-type MUGFET, respectively, orvice versa). Alternatively, the MUGFETs 101 a and 101 b can be the sametype of MUGFET (e.g., both n-type MUGFETs or both p-type MUGFETs).

Referring to FIG. 12, another embodiment of a method of forming asemiconductor structure with multiple fin-shaped channel regions havingdifferent widths can comprise providing a semiconductor-on-insulator(SOI) wafer (212, see detailed discussion above regarding process step12 of FIG. 1). Next, a trench isolation structure 110 (e.g., a shallowtrench isolation (STI) structure) can be formed so as to define, in thesemiconductor layer on the insulator layer 105, a first semiconductorregion 120 a for a first non-planar multi-gate field effect transistor(MUGFET) and a second semiconductor region 120 b, positioned laterallyadjacent to the first semiconductor region 120 a, for a second MUGFET(214, see FIGS. 2A and 2B and detail discussion above regarding processstep 14 of FIG. 1).

After the first semiconductor region 120 a and second semiconductorregion 120 b are defined at process 214, a first dielectric body 151 acan be formed on the first semiconductor region 120 a and at the sametime a second dielectric body 151 b can be formed on the secondsemiconductor region 120 b (216, see FIGS. 3A and 3B and detaileddiscussion above regarding process step 16 of FIG. 1). For example, thefirst dielectric body 151 a and the second dielectric body 151 b canspecifically be formed so that they are essentially identical, so thatthey traverse the length of the first semiconductor region 120 a andsecond semiconductor region 120 b, respectively, and further so thatthey are narrower than the first semiconductor region 120 a and thesecond semiconductor region 120 b, respectively. This can beaccomplished, for example, by depositing a first dielectric hardmasklayer and, then, patterning the first dielectric hardmask layerlithographically to form the discrete dielectric bodies 151 a-b.

Once the first dielectric body 151 a and second dielectric body 151 bare formed, first dielectric spacers 152 a can be formed on firstopposing sides 153 a of the first dielectric body 152 a and at the sametime second dielectric spacers 152 b can be formed on the secondopposing sides 153 b of the second dielectric body 152 b (218, see FIGS.13A-13B). This can be accomplished, for example, by depositing aconformal second dielectric hardmask layer. The second dielectrichardmask layer can be selectively and anisotropically etched to formfirst dielectric spacers 152 a on the opposing sides 153 a of the firstdielectric body 151 a and second dielectric spacers 152 b on theopposing sides 153 b of the second dielectric body 151 b. This seconddielectric hardmask layer can comprise a different dielectric hardmaskmaterial than the first dielectric hardmask layer that was previouslyused at process 216 to form the first and second dielectric bodies 151a-b.

Next, the first semiconductor region 120 a can be masked and the seconddielectric body 151 a can be selectively removed (219, see FIGS. 14A and14B). As mentioned above, the dielectric bodies 151 a-b and thedielectric spacers 152 a-b should be formed so that they comprisedifferent dielectric materials and, particularly, different dielectricmaterials that allow for selective etching of the second dielectric body151 b over the second dielectric spacers 152 b. For example, thedielectric bodies 151 a-b can be formed with silicon nitride and thedielectric spacers 152 a-b can be formed with silicon oxide, siliconoxynitride or silicon carbide. These exemplary dielectric materials areoffered for illustration purposes only and it should be understood thatother combinations of dielectric materials may alternatively be used.Following process step 219, the mask on the first semiconductor region120 a can be removed.

Next, a sacrificial layer 195 (i.e., a sacrificial gate structure, areplacement gate structure, etc.) can be formed (220, see FIGS.15A-15B). This sacrificial layer 195 can comprise, for example, apolysilicon layer or other material that can be selectively etched atprocess 214, discussed below. Specifically, this sacrificial layer 195can be deposited and patterned (e.g., lithographically) so that ittraverses the center portion 131 a (i.e., the first center portion orfirst designated channel region) of the first semiconductor region 120a, leaving the end portions 132 a of the first semiconductor region 120a (i.e., the first end portions) exposed and also traversing the centerportion 131 b (i.e., the second center portion or second designatedchannel region) of the second semiconductor region 120 b, leaving theend portions 132 b of the second semiconductor region 120 b (i.e., thesecond end portions) exposed. It should be noted that this process 220will remove all remaining dielectric material (i.e., the firstdielectric body 151 a, first dielectric spacers 152 a, and seconddielectric spacers 152 b) from above the first and second end portions132 a-b, while leaving intact the dielectric material above the firstand second center portions 131 a-b.

After the sacrificial layer 195 is formed at process 220, conventionalMUGFET processing can be performed (222). This conventional MUGFETprocessing can include, but is not limited to, source/drain extensiondopant implantation, halo dopant implantation, gate sidewall spacer 162formation (see FIG. 16), source/drain dopant implantation into the firstand second end portions 132 a-b and silicide layer formation on the topsurfaces of the first and second end portions 132 a-b. It should benoted that this conventional processing will vary depending upon whetherthe MUGFETs being formed in the first semiconductor region 120 a and thesecond semiconductor region are to have the same conductivity type(e.g., n-type or p-type) or opposite conductivity types (e.g., n-typeand p-type, respectively). For example, if the MUGFETs are to have thesame conductivity type the various dopant implantation processes can beperformed essentially simultaneously. However, if the MUGFETs are tohave opposite conductivity types, the end portions of one semiconductorregion can be masked while dopant implantation is performed on the endportions of the other semiconductor region and vice versa.

Next, a blanket dielectric layer 115 (e.g., an interlayer dielectric)can be formed (e.g., deposited) such that it extends over thesacrificial layer 195, the gate sidewall spacers 162, the first endportions 132 a and the second end portions 132 b. The blanket dielectriclayer 115 can then be planarized (e.g., using a conventional chemicalmechanical polishing (CMP) process) to expose the top surface of thesacrificial layer 195 (224, see FIG. 17). Once exposed, the sacrificiallayer 195 can be selectively removed (e.g., using a selective etchprocess) (226, see FIGS. 18A and 18B). This process 226 exposes theremaining portions of the first dielectric body 151 a and the firstdielectric spacers 152 a as well as sections of the first center portion131 a of the first semiconductor region 120 a between the firstdielectric spacers 152 a and the isolation structure 110. This process226 also exposes the remaining portions of the second dielectric spacers152 b as well as sections of the second center portion 131 b of thesecond semiconductor region 120 b between each of the second dielectricspacers 152 b and further between the second dielectric spacers 152 band the isolation structure 110. Finally, this process 226 leaves thegate sidewall spacers 162 and dielectric layer 115 essentially intact.

Next, a directional etch process (e.g., a reactive ion etch (RIE)process) can be performed so as to remove exposed semiconductor materialwithin the first center portion 131 a of the first semiconductor region120 a and the second center portion 131 b of the second semiconductorregions 120 b (228, see FIGS. 19A-19C). During this etch process 228,the dielectric layer 115 on the first end portions 132 a and the secondend portions 132 b, the first dielectric body 151 a and the firstdielectric spacers 152 a on the first center portion 131 a and thesecond dielectric spacers 152 b on the second center portion 131 b areused as masks. Thus, this directional etch process 228 forms openings196 a-196 b that stop on the insulator layer 105 and, thereby turns thefirst center portion 131 a (i.e., the first channel region) of the firstsemiconductor region 120 a into an essentially fin-shaped structure andthe second center portion 131 b (i.e., the second channel region) of thesecond semiconductor region 120 b into two parallel essentiallyfin-shaped structures 131 b-1 and 131 b-2. More particularly, as aresult of this directional etch process 228, the first center portion131 b of the first semiconductor region 120 a will be narrower than thefirst end portions 132 b and will have a first width 141 a that isessentially equal to the combined width of the first dielectric body 151a and the first dielectric spacers 152 a. Also as a result of thisdirectional etch process 228, the second center portion 131 b will havetwo parallel sections 131 b-1 and 131 b-2. Each of theses parallelsections 131 b-1 and 131 b-2 will be essentially fin-shaped and willhave a second width 141 b. This second width 141 b will be less than thefirst width 141 a of the first center portion 131 a and, specifically,will be essentially equal to the width of a corresponding one of thesecond dielectric spacers 152 b (see FIG. 19B).

After performing the directional etch process 228, a gate structure 190can be formed on the exposed first sidewalls 130 a of the first centerportion 131 a and on the exposed second sidewalls 130 b of the parallelsections 131 b-1 and 131 b-2 of the second center portion 131 b (232,see FIGS. 20A-B). For example, a conformal gate dielectric layer 191(e.g., a gate oxide layer, a high-k gate dielectric layer or othersuitable gate dielectric layer) can be formed (e.g., deposited) and agate conductor layer 192 (e.g., a metal gate conductor layer, apolysilicon gate conductor layer, a dual work function gate conductorlayer or other suitable gate conductor layer) can be formed (e.g.,deposited) on the gate dielectric layer 191. The gate conductor layer192 and gate dielectric layer 191 can then be patterned (e.g.,lithographically), thereby creating a gate structure 190 that traversesthe center portions 131 a-b and fills the openings 196 a-b. As a result,this gate structure 190 is positioned on the first sidewalls 130 a ofthe first center portion 131 a and also on the second sidewalls 130 b ofthe parallel sections 131 b-1 and 131 b-2 of the second center portion131 b.

It should be noted that, in this case, the first dielectric body 151 aand first dielectric spacers 152 a will function as a first isolatingcap 150 a that electrically isolates the top surface of the first centerportion 131 a from the gate structure 190 and, thereby ensures that onlytwo-dimensional field effects are exhibited by the first center portion131 a. Similarly, the second dielectric spacers 152 b will function asdiscrete second isolating caps 150 b that electrically isolate the topsurfaces of the parallel sections 131 b-1 and 131 b-2 from the gatestructure 190 and, thereby ensure that only two-dimensional fieldeffects are exhibited by the parallel sections 131 b-1 and 131 b-2.However, optionally, prior to forming the gate structure 190 at process232, dielectric material can be selectively removed from above the firstcenter portion 131 a and/or from above the parallel sections 131 b-1 and131 b-2 of the second center portion 131 b. Removing this dielectricmaterial allows three-dimensional field effects to be exhibited (230).

After the gate structure 190 is formed at process 332, additionalconventional processing can be performed in order to complete thesingle-fin MUGFET 101 a and multi-fin MUGFET 101 c (234). Thisadditional processing can include, but is not limited to, deposition ofinterlayer dielectric material, contact formation, etc.

FIG. 20A is vertical cross-section illustration of an embodiment of asemiconductor structure 100B formed according to the method of FIG. 12such that it has multiple fin-shaped channel regions 131 a, 131 b-1, 131b-2 having different widths 141 a, 141 b and, optionally, differentlyconfigured isolating caps 150 a, 150 b. FIG. 20B is a horizontalcross-section illustration of the same semiconductor structure 100B.

Referring to FIG. 20A, this semiconductor structure 100B can comprise asilicon-on-insulator (SOI) structure. Specifically, the structure 100Bcan comprise an insulator layer 105 (e.g., a buried oxide (BOX) layer orother suitable insulator layer) and a semiconductor layer (e.g., asilicon layer or other suitable semiconductor layer) on the insulatorlayer 105. A trench isolation structure 110 (e.g., a shallow trenchisolation (STI) structure) can extend vertically through thesemiconductor layer to the insulator layer 105 and can define a firstsemiconductor region 120 a for a first MUGFET 101 a and a secondsemiconductor region 120 b, positioned laterally adjacent to the firstsemiconductor region 120 a, for a second MUGFET 101 c and, particularly,a multi-fin MUGFET 101 c (see also FIG. 20B). That is, a trenchisolation structure 110 on the insulator layer 105 can laterallysurround the first semiconductor region 120 a and the secondsemiconductor region 120 b such that the first semiconductor region 120a is electrically isolated from the second semiconductor region 120 b.

The first semiconductor region 120 a can have first end portions 132 aand a first center portion 131 a positioned laterally between the firstend portions 132 a. The first center portion 131 a can comprise a firstchannel region for the first MUGFET 101 a. The first center portion 131a can further be narrower than the first end portions 132 b, can haveopposing sidewalls 130 a (e.g., can be essentially fin-shaped), can bephysically separated from the isolation structure 110 and can have afirst width 141 a. The first end portions 132 a can comprise firstsource/drain regions and, optionally, other component regions (e.g.,first halo regions, first source/drain extension regions, etc.) for thefirst MUGFET 101 a. Optionally, a first isolating cap 150 a can bepositioned on the top surface of the first center portion 131 a and canhave the same first width 141 a. The first isolating cap 150 a cancomprise a dielectric body 151 a positioned laterally between twodielectric spacers 152 a. The first width 141 a of the first centerportion 131 a of the first semiconductor region 120 a can be essentiallyequal to the combined width of the dielectric body 151 a and thedielectric spacers 152 a.

The second semiconductor region 120 b can have second end portions 132 band a second center portion 131 b positioned laterally between thesecond end portions 132 b. The second center portion 131 b can comprisea second channel region for the second MUGFET 101 b. The second centerportion 131 b can further be narrower than the second end portions 132 band can comprise two parallel sections 131 b-1 and 131 b-2. Each ofthese parallel sections 131 b-1 and 131 b-2 can have opposing sidewalls130 b (e.g., can be essentially fin-shaped), can be physically separatedfrom the isolation structure 110 and can have a second width 141 b thatis less than the first width 141 a. The second end portions 132 b cancomprise second source/drain regions and, optionally, other componentregions (e.g., second halo regions, second source/drain extensionregions, etc.) for the second MUGFET 101 c. Optionally, second isolatingcaps 150 b can be positioned on the parallel sections 131 b-1 and 131b-2 and can have the same second width 141 b as the parallel sections.Each second isolating cap 150 b can comprise a dielectric spacer 152 bthat is essentially identical to one of the dielectric spacers 152 a ofthe first isolating cap 150 a.

A gate structure 190 can traverse the center portions 131 a and 131 b ofboth semiconductor regions 120 a, 120 b. Specifically, a conformal gatedielectric layer 191 (e.g., a gate oxide layer, a high-k gate dielectriclayer or other suitable gate dielectric layer) can be positioned on thefirst opposing sidewalls 130 a of the first center portion 131 a of thefirst semiconductor region 120 a and also on the second opposingsidewalls 130 b of each of the parallel sections 131 b-1 and 131 b-2 ofthe second center portion 131 b of the second semiconductor regions 120b. A gate conductor layer 192 (e.g., a metal gate conductor layer, apolysilicon gate conductor layer, a dual work function gate conductorlayer or other suitable gate conductor layer) can be positioned on thegate dielectric layer 191. Optionally, the top surface of the firstcenter portion 131 a can be electrically isolated from the gatestructure 190 by the first isolating cap 150 a so that the first centerportion 131 a exhibits only two-dimensional field effects. However,without the first isolating cap 150 a, the first center portion 131 acan exhibit three-dimensional field effects. Optionally, the topsurfaces of each of the parallel sections 131 b-1 and 131 b-2 of thesecond center portion 131 b can be electrically isolated from the gatestructure 190 by second isolating caps 150 b so each of the parallelsections also only exhibit two-dimensional field effects. However,without the second isolating caps 150 b, the parallel sections of thesecond center portion 131 b can exhibit three-dimensional field effects.

As with the semiconductor structure 100A, the semiconductor structure100B can further comprise gate sidewall spacers positioned on opposingsides of the gate structure 190, optional metal silicide layerspositioned on the top surfaces of the first end portions 132 a andsecond end portions 132 b, respectively, and an interlayer dielectricmaterial positioned on the metal silicide layers above the first andsecond end portions 132 a, 132 b of the first and second semiconductorregions 120 a, 120 b, respectively, and adjacent to the gate sidewallspacers.

In the above-discussed semiconductor structure 100B, the dielectric body151 a and the dielectric spacers 152 a-b that make up the isolating caps150 a-b can comprise different dielectric materials and, particularly,different dielectric materials that allow for selective etching duringprocessing. For example, the dielectric body 151 a can comprise siliconnitride and the dielectric spacers 152 a-b can comprise silicon oxide,silicon oxynitride or silicon carbide. These exemplary dielectricmaterials are offered for illustration purposes only. It should beunderstood that other combinations of dielectric materials mayalternatively be used. Additionally, in the above-discussedsemiconductor structure 100B, the first MUGFET 101 a and second MUGFET101 c can be different types of MUGFETs (e.g., an n-type MUGFET and ap-type MUGFET, respectively, or vice versa). Alternatively, the MUGFETs101 a and 101 c can be the same type of MUGFET (e.g., both n-typeMUGFETs or both p-type MUGFETs).

In the exemplary method embodiments described above multiple fin-shapedchannel regions with different widths for different MUGFETs (e.g., afirst MUGFET and a second MUGFET) are formed in different semiconductorregions (i.e., a first semiconductor region and a second semiconductorregion). However, it should be understood that, if desired (e.g., totune device performance) such multiple fin-shaped channel regions withdifferent widths can be formed in the same semiconductor region for thesame MUGFET. For example, FIG. 21A is vertical cross-sectionillustration of an embodiment of a semiconductor structure 300 havingmultiple fin-shaped channel regions 331 a, 331 b, 331 c-1, 331 c-2having different widths 341 a, 341 b and 341 c and being incorporatedinto a single MUGFET 301. FIG. 20B is a horizontal cross-sectionillustration of the same semiconductor structure 300.

Specifically, referring to FIGS. 21A-21B in combination, thissemiconductor structure 300 can comprise an insulator layer 305 (e.g., aburied oxide (BOX) layer or other suitable insulator layer) and asemiconductor layer (e.g., a silicon layer or other suitablesemiconductor layer) on the insulator layer 305. A trench isolationstructure 310 (e.g., a shallow trench isolation (STI) structure) canextend vertically through the semiconductor layer to the insulator layer305 and can define a semiconductor region 320. That is, a trenchisolation structure 310 on the insulator layer 105 can laterallysurround the semiconductor region 320. The semiconductor region 320 canhave end portions 332 and a center portion between the end portions 332.

The end portions 332 can comprise source/drain regions and, optionally,other component regions (e.g., first halo regions, first source/drainextension regions, etc.) for the MUGFET 301.

The center portion can be narrower than the end portions 332 and cancomprise a plurality of parallel essentially fin-shaped sections (e.g.,331 a, 331 b, 331 c-1 and 331 c-2), each comprising a channel region. Atleast two of the parallel sections (e.g., 331 a, 331 b, 331 c-1 or 331c-2) can have different widths (e.g., 341 a, 341 b, 341 c).

These different widths (e.g., 341 a, 341 b, 341 c) can be defined duringprocessing by differently configured isolating caps 350 a, 350 b and 350c on the top surfaces of the sections 331 a, 331 b, 331 c-1, 331 c-2.The isolating caps 350 a, 350 b and 350 c can, optionally, remain afterprocessing to ensure that the corresponding channel regions exhibittwo-dimensional field effects.

For example, a first isolating cap 350 a can be positioned on the topsurface of the first section 331 a. This first isolating cap 350 a cancomprise a dielectric body 351 a positioned laterally between dielectricspacers 352 a. The width 341 a of the first section 331 a can beessentially equal to the combined width of the dielectric body 351 a andthe dielectric spacers 352 a. A second isolating cap 350 b can bepositioned on the top surface of the second section 331 b. This secondisolating cap 350 b can comprise a dielectric body 351 b withoutdielectric spacers. The width 341 b of the second section 331 b can beessentially equal to the width of the dielectric body 351 b and thedielectric body 351 b can be essentially identical to the dielectricbody 351 a of the first isolating cap 350 a. Thus, the width 341 b ofthe second section 331 b will be less than the width 341 a of the firstsection 331 a. Additionally or alternatively, third isolating caps 350 bcan be positioned on the top surfaces of the sections 331 c-1 and 331c-2. The third isolating caps 350 c can each comprise a dielectricspacer 352 c. The width 341 c of the each third section 331 c can beessentially equal to the width of a corresponding dielectric spacer 352c and the corresponding dielectric spacer 352 c can be essentiallyidentical to one of the dielectric spacers 352 a of the first isolatingcap 350 a. Thus, the width 341 c of the each third section 331 c will beless than the width 341 a of the first section 331 a.

It should be noted that in this structure 300, the dielectric bodies andthe dielectric spacers can comprise different dielectric materials and,particularly, different dielectric materials that allow for selectiveetching during processing. For example, the dielectric bodies cancomprise silicon nitride and the dielectric spacers can comprise siliconoxide, silicon oxynitride or silicon carbide. These exemplary dielectricmaterials are offered for illustration purposes only. It should beunderstood that other combinations of dielectric materials mayalternatively be used.

Additionally, a gate structure 390 can traverse the parallel sections(e.g., 331 a, 331 b, etc.). Specifically, a conformal gate dielectriclayer 391 (e.g., a gate oxide layer, a high-k gate dielectric layer orother suitable gate dielectric layer) can be positioned on the opposingsidewalls 330 a, 330 b, 330 c of each of the sections 331 a, 331 b, 331c-1, 331 c-2. A gate conductor layer 392 (e.g., a metal gate conductorlayer, a polysilicon gate conductor layer, a dual work function gateconductor layer or other suitable gate conductor layer) can bepositioned on the gate dielectric layer 391. The top surfaces of each ofthese sections 331 a, 331 b, 331 c-1, 331 c-2 can, optionally, beelectrically isolated from the gate structure 390 by the isolating caps350 a-c so that each section only exhibits two-dimensional fieldeffects. However, if, during processing any of the isolating caps 350a-c are removed, the corresponding sections will exhibitthree-dimensional field effects.

It should be understood that the method embodiments, as described above,are used in the fabrication of integrated circuit chips. The resultingintegrated circuit chips can be distributed by the fabricator in rawwafer form (that is, as a single wafer that has multiple unpackagedchips), as a bare die, or in a packaged form. In the latter case thechip is mounted in a single chip package (such as a plastic carrier,with leads that are affixed to a motherboard or other higher levelcarrier) or in a multichip package (such as a ceramic carrier that haseither or both surface interconnections or buried interconnections). Inany case the chip is then integrated with other chips, discrete circuitelements, and/or other signal processing devices as part of either (a)an intermediate product, such as a motherboard, or (b) an end product.The end product can be any product that includes integrated circuitchips, ranging from toys and other low-end applications to advancedcomputer products having a display, a keyboard or other input device,and a central processor.

Additionally, it should be understood that the terminology used hereinis for the purpose of describing particular embodiments only and is notintended to be limiting of the invention. As used herein, the singularforms “a”, “an” and “the” are intended to include the plural forms aswell, unless the context clearly indicates otherwise. It will be furtherunderstood that the terms “comprises” and/or “comprising,” when used inthis specification, specify the presence of stated features, integers,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Furthermore, the corresponding structures, materials, acts, andequivalents of all means or step plus function elements in the claimsbelow are intended to include any structure, material, or act forperforming the function in combination with other claimed elements asspecifically claimed. The description of the present invention has beenpresented for purposes of illustration and description, but is notintended to be exhaustive or limited to the invention in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art without departing from the scope and spiritof the invention. The embodiment was chosen and described in order tobest explain the principles of the invention and the practicalapplication, and to enable others of ordinary skill in the art tounderstand the invention for various embodiments with variousmodifications as are suited to the particular use contemplated.

Therefore, disclosed above are embodiments of a damascene method forforming a semiconductor structure and also the resulting semiconductorstructure having multiple fin-shaped channel regions with differentwidths. During damascene processing and, particularly, aftersource/drain and other dopant implantation processes are performed,fin-shaped channel regions are etched using differently configuredisolating caps as masks to define the different channel region widths.For example, a wide width isolating cap can comprise a dielectric bodypositioned laterally between dielectric spacers and can be used as amask to define a relatively wide width channel region; a medium widthisolating cap can comprise a dielectric body alone and can be used as amask to define a medium width channel region and/or a narrow widthisolating cap can comprise a dielectric spacer alone and can be used asa mask to define a relatively narrow width channel region. Thesemultiple fin-shaped channel regions with different widths can beincorporated into either multiple different non-planar multi-gate fieldeffect transistors (MUGFETs) or a single MUGFET. By defining thefin-shaped channel regions after source/drain and other dopantimplantation processes are performed, channel region damage can beavoided.

1. A method of forming a semiconductor structure, said methodcomprising: forming a trench isolation structure to define, in asemiconductor layer, a first semiconductor region and a secondsemiconductor region positioned laterally adjacent to said firstsemiconductor region; forming a first dielectric body on said firstsemiconductor region and a second dielectric body on said secondsemiconductor region; forming first dielectric spacers on first opposingsides of said first dielectric body; forming a sacrificial layertraversing a first center portion of said first semiconductor regionover said first dielectric body and said first dielectric spacers andalso traversing a second center portion of said second semiconductorregion over said second dielectric body; depositing a blanket dielectriclayer so as to cover first end portions of said first semiconductorregion and second end portions of said second semiconductor region;planarizing said dielectric layer to expose said sacrificial layer;selectively removing said sacrificial layer; performing a directionaletch process to remove exposed semiconductor material within said firstcenter portion and said second center portion such that, after saidperforming of said directional etch process, said first center portionhas a first width and said second center portion has a second width thatis less than said first width.
 2. The method of claim 1, furthercomprising: during said forming of said first dielectric spacers alsoforming second dielectric spacers on second opposing sides of saidsecond dielectric body; and after said forming of said first dielectricspacers and said second dielectric spacers, selectively removing saidsecond dielectric spacers.
 3. The method of claim 1, said directionaletch process being performed using, as masks, said dielectric layer onsaid first end portions and said second end portions, said firstdielectric body and said first dielectric spacers on said first centerportion and said second dielectric body on said second center portion.4. The method of claim 1, said first dielectric body and said seconddielectric body being formed with a first dielectric material and saidfirst dielectric spacers and said second dielectric spacers being formedwith a second dielectric material different from said first dielectricmaterial.
 5. The method of claim 1, further comprising, after saidperforming of said directional etch process, forming a gate structure onexposed first sidewalls of said first center portion and on exposedsecond sidewalls of said second center portion.
 6. The method of claim5, further comprising, before said forming of said gate structure,selectively removing dielectric material from above at least one of saidfirst center portion and said second center portion.
 7. A method offorming a semiconductor structure, said method comprising: forming atrench isolation structure to define, in a semiconductor layer, a firstsemiconductor region and a second semiconductor region positionedlaterally adjacent to said first semiconductor region; forming a firstdielectric body on said first semiconductor region and a seconddielectric body on said second semiconductor region; forming firstdielectric spacers on first opposing sides of said first dielectric bodyand second dielectric spacers on second opposing sides of said seconddielectric body; selectively removing said second dielectric body;forming a sacrificial layer traversing a first center portion of saidfirst semiconductor region over said first dielectric body and saidfirst dielectric spacers and also traversing a second center portion ofsaid second semiconductor region over said second dielectric spacers;depositing a blanket dielectric layer so as to cover first end portionsof said first semiconductor region and second end portions of saidsecond semiconductor region; planarizing said dielectric layer to exposesaid sacrificial layer; selectively removing said sacrificial layer;performing a directional etch process to remove exposed semiconductormaterial within said first center portion and said second center portionsuch that, after said performing of said directional etch process, saidfirst center portion has a first width and said second center portioncomprises two parallel sections, each of said parallel sections having asecond width that is less than said first width.
 8. The method of claim7, said directional etch process being performed using, as masks, saiddielectric layer on said first end portions and said second endportions, said first dielectric body and said first dielectric spacerson said first center portion and said second dielectric spacers on saidsecond center portion.
 9. The method of claim 7, said first dielectricbody and said second dielectric body being formed with a firstdielectric material, said first dielectric spacers and said seconddielectric spacers being formed with a second dielectric materialdifferent from said first dielectric material.
 10. The method of claim7, further comprising: after said performing of said directional etchprocess, forming a gate structure on first sidewalls of said firstcenter portion and on second sidewalls of said parallel sections of saidsecond center portion.